1. Field of the Invention
The present invention relates generally to hand-held flashlights and more specifically to flashlights emitting multiple colors produced by light emitting diodes (LEDs).
2. Description of the Prior Art
Light emitting diodes (LEDs) have provided significant advances in portable light sources, such as flashlights. Conventional flashlights use relatively fragile incandescent lamps with a short operating life and high power consumption. In the 1950s and 1960s, the first widespread reports were published of infrared emission from a semiconductor alloy when provided with electric current, see, e.g., U.S. Pat. No. 3,293,513, to Texas Instruments, Inc., titled “Semiconductor radiant diode”. LEDs are able to emit a certain wavelength of light, which at certain wavelengths, forms visible light, based on the semiconductor material. Different colors can be emitted using various materials and combinations of materials, which includes the emission of red, orange, yellow, green, blue, violet, and ultraviolet radiation.
LEDs produce more intense light per watt than do incandescent bulbs, which is useful in the technology of a flashlight that requires long-term usage and whose failure carries serious consequences. Additionally, LEDs usually fail by dimming over time, providing some warning of their impending failure to the user. LEDS may last up to 50,000 hours, whereas fluorescent tubes are rated to about 30,000 hours and incandescent bulbs average 1,000 to 2,000 hours of usage. LEDs can emit light of a certain color, which is useful in situations that require specific types and intensities of light, such as hunting, night-based research, or military operations. LEDs are dimmable and focusable, unlike incandescent and fluorescent light sources. LEDs have no detrimental effects from frequent on-off cycling. LEDs are solid-state, which makes it much more difficult to break them or make them unusable through accidents like droppage.
White light LEDs were originally produced through a combination of red, green, and blue LEDs. Currently, white light LEDs are usually modified blue LEDs which emit blue light through a yellowish phosphor coating, the result of this is a mixture of blue and yellow light which gives the appearance of white light. The newest method of producing white light LEDs uses homoepitaxially grown zinc selenide on a zinc selenide substrate, which emits blue light and yellow light simultaneously.
Currently, there are a number of flashlights on the market that use LEDs with different wavelengths of emission. Flashlights have been produced that contain multiple LED sources in a single structure. This solves the problem of needing separate flashlights for multiple modalities.
Current multi-color flashlights use a single switch to cycle through the various colors. This cycling results in the white LED being lit in every cycle. However cycling through the white light leads to safety hazards in a number of situations, including aviation, military and police applications, where preserving night vision is necessary; white light is readily picked by and intensified by standard night vision technology. Additionally, colored LEDs are thought to be invisible to many game animals and will not spook animals like white light. Other LEDs include ultraviolet (UV) and infrared (IR) LEDs as well. UV LEDs are used for identifying security holograms and markings on money, drivers' licenses and passports. IR LEDs are used in military operations with night vision apparatus to identify friendly combatants.
One configuration that avoids cycling through the white LED has three dedicated switches aligned along the same side of the handle, with each switch controlling one color. However, this configuration proves cumbersome, making the flashlight too long and expensive. Another alternative is exemplified by the “4 Color Recon Torch” flashlight made by Coast Products, Inc, which has four switches, one for each of four colored LEDs, see http://www.coastportland.com. However, these switches are spread out on opposite sides of the flashlight. While this shortens the length of the flashlight, it results in the operator not knowing which button they are pushing in the dark because the orientation of the flashlight in the operator's hand may not always be known.
A multiple switch technology is needed to regulate the colored LEDs separately from the white LED. Previous technologies do not provide satisfactory solutions. For instance, U.S. Pat. No. 7,293,893 to assignee Surefire LLC, titled “Flashlight with adjustable color selector switch,” describes a flashlight having an elongated body having opposed first and second ends. A first lamp is a high-intensity variable brightness white light source located at the first end. A number of additional lamps are positioned at the first end. The additional lamps include at least two different output wavelengths different from each other and from the first lamp. A first switch on the flashlight selectively operates to select the output wavelength of the flashlight by selectively enabling different lamps based on the condition of the switch. A power storage element and control circuitry are connected to the lamps and to the switch. However, the bulb is still cycled through the white and colored LEDs by use of one switch. One would not know which color is being activated, which could accidentally lead to white being activated which may be fatal in, for instance, night military operations.
Thus, there remains a need for a multimodal flashlight with white light controlled by one switch and multiple functions controlled by a second switch, including the ability to cycle through several desired non-white colors.